Sorry to say that I have no photos. However, I did learn something new about my exposure box/cylinder and that I must make a new attachment for it. With the addition of some white vinyl and a small piece of glass, the bottom portion of the exposure box/cylinder makes an excellent light box for layout, alignment, and trimming purposes. I used this setup for aligning both transparency layers, spot fusing the transparencies together, and for trimming the double layer transparencies to size. The combination of this setup along with the film cutter/fuser, definitely helps to make less translucent double layer laser transparencies. It all works together pretty nice.
Hello Bruce..
'
A big problem I found using Laser printers is with Copper Pours.
'
I'm working with a lot of RF here lately and I need a good ground plain (copper pour) to help propagate the RF.
'
Have you been able to print copper pours with your laser printer with out making a mess?
If you are referring to a mess with the printer.... If I remember correctly, you said you were using 3M transparency film. I would imagine that film is very similar to the film I initially used and it gave me many headaches. With the premium transparency film that I received from the local graphic arts supply house, the results are much better in all respects, including ground planes.
I apologize for the delay, but I just noticed your last post.
GC-Prevue prints out perfect masks for me. In fact, it allows me to add extra layers, such as the mounting holes, and prints them out as well.
There are three possible states for each layer, which are View, Edit, and Hide. When the layers are listed, there will be either an E, V, or H, at the beginning of the layer to represent its state. The layers should be in View state to allow printing.
To save you some trouble, I have attached a project file that includes the mounting holes. Perhaps this will work better for you.
Bruce
EDIT: Additionally, all layers that you do not want printed must be hidden.
EDIT: When printing, select the checkbox for: "Print all data in black"
EDIT: And of course, when printing the top layer, select the checkbox for: "Print as bottom view"
When spraying your photo mask films with Acrylic Krylon Crystal Clear Satin, the utmost care must be taken not to completely saturate the image, otherwise the toner will bleed to unwanted areas. It takes a few times to get the hang of it. And if it looks as though it has bled, believe it. Just print another mask and try again, because wasting a little film is much better than wasting additional time and board material. Trust me I know.
Watching this thread with interest. At our hackerspace we do both laser toner transfer and PCB milling. Never done photo-resist boards so interested to see the results.
In regard to the tips that I provided in Post #69, there is one thing I forgot to mention. Retain the default setting of "Layers To Print: VISIBLE" in the Print Setup property sheet, when using the tips I provided, or you can select individual layers from the Print Setup property sheet if you choose to do so, which will also print a hidden layer without altering the visibilty within the user interface view.
The blades for the film cutter/fuser are burning up to often. They work great, but it is turning out to be a pain creating new blades all the time. As mentioned in Post #58, I am currently bending 0.047" music wire into a U-shaped form, and then sharpening one corner as described in Item #4 of the directions for that same post. I am not sure if they are burning up quickly because the music wire is tempered, too much carbon buildup on the blade from cutting the film, or some other reason.
I would like to find a solution with a little bit of longevity. Does anyone have any suggestions?
The blades for the film cutter/fuser are burning up to often. They work great, but it is turning out to be a pain creating new blades all the time. As mentioned in Post #59, I am currently bending 0.047" music wire into a U-shaped form, and then sharpening one corner as described in Item #4 of the directions for that same post. I am not sure if they are burning up quickly because the music wire is tempered, too much carbon buildup on the blade from cutting the film, or some other reason.
I would like to find a solution with a little bit of longevity. Does anyone have any suggestions?
Bruce
Bruce,
I use these a lot for cutting foam shapes. They are actual blades and hold up very well. The price of admission is a little high though.
However I was thinking more along the lines of my homemade cutter, with a different cutting blade. I found some 3/8 crown X 5/8 leg staples, and I have been experiment with them. If I could perfect the use of those, that would drastically cut the time required for making blades.
Referring to Post #75. In an attempt to find a better blade material, I tried using 1/16" tie wire. It appeared that the wire held up well, but there was a drastic increase in the plastic buildup as compared to the 0.047" music wire. By the time I finished removing all the buildup, I had ruined the best looking photo mask that I have had in my hands.
Ohhh, and I finally kicked the circuit breaker in the battery charger with this last experiment
For a while, I have been considering the modification of a double-edged shaving blade. I may try that next. I will keep you posted.
I just had a fantastic idea!!!! One of those "A DUH" moments. The wire bending CNC is loaded up with 0.032" music wire. I will attempt to hand bend a prototype, and if it works out well, I could just write a small program to spit out a couple thousand
The 0.032" music wire seemed to do okay with very little buildup, however, it seemed to burn out just a little faster than the 0.047" music wire. Additionally, it seemed that the 0.032" wire did not fuse the layers together as well as the 0.047" wire. I plan to do a little more experimenting with this wire size, because it will enable me to make my blades much faster using the wire bending CNC and I have lot of wire in this size. My main goal now is to get the two layers to fuse together properly. If I can achieve that, then I believe I will be able to create some nice masks fairly quickly and without the hassle of using a torch.
On a side note, when filing down any remaining plastic buildup, use a new or very clean file. Oil, dirt, and old metal shavings remaining on used files quickly destroy a good looking mask. Once again, I am speaking from the little experience I have gained through this experimentation process. However, I did previously mention to perform the filing procedure on the edge of a metal plate, so a new file will eventually gather small metal shavings. Just remember to keep the file as clean as possible and work in a very clean environment to keep the masks looking nice.
Oh, and there is something else you should know. If you make a film cutter/fuser and cut upon a piece of glass as I describe, each cut will leave a line of plastic resin upon your glass plate. This plastic resin can be removed with laquer thinner. Additionally, pressure and heat from the cutting action will cause permanent scratching upon the glass surface. Considering that the cutting wire gets red hot, if you leave it in one place for too long, it will melt the glass, thus making a permanent indentation.
As it turns out, the 0.032" dia. music wire works pretty good for cutting and fusing the two layers of film together, however it requires several passes through the cut. Upon completion of trimming the mask, there is very little touchup required to remove the plastic buildup. I am sure there are probably much better solutions available, but this works pretty darn good, and considering that I have an abundance of this particular wire size and a machine to quickly bend the wire into shape and cut it, I believe this is the best solution for me. Please note, that in accordance with previous experiments for cutting blades, these cutting blades must also be sharpened as described in Item #4 of the Directions section of Post #58.
As I mentioned, this is a good solution for me, but if you decide to make a film cutter/fuser, you may want to experiment a bit more to find or create something that works much better. If you do find something that works much better, please let me know.
Bruce - I was wondering about the physics of the smaller wire working better. Does the smaller wire heat up faster from the friction and thus fuse the layers better and burn off buildup better or am I not visualizing the process properly?
Does the smaller wire heat up faster from the friction and thus fuse the layers better and burn off buildup better or am I not visualizing the process properly?
The smaller wire heats up faster due to resistance.
The main idea is not to burn the plastic, but to slice through it by a melting process. As the blade is slicing through the two layers of film, the blade is hot on both sides, which results in both layers on both sides of the blade being melted and joined together.
As for the buildup, I believe this is all related to the actual thickness and bevel of the cutting portion of the blade. For instance, if you have a lump of bread dough on the counter and you slice through it with a razor blade, you will not have much buildup on either side of the blade. On the other hand, if you attempt to slice through the dough with the handle end of a butter knife, I would imagine the buildup would be pretty significant on both sides.
Remember, you do not want to burn anything, you want to melt it.
As a side note, in the past, I had been tacking the layers together by just placing the blade in one spot and holding it there for a second or two. This actually burns the plastic in these particular spots, and releases a very pugnant odor. Burning plastic fumes can be very harmful and may even contain cyanide, so burning the plastic should be avoided if at all possible. Tacking can also be achieved by a slicing motion through the trim areas of the films and this is my current method of tacking.
Thanks Bruce. I understand now. In skimming through the thread I picked up on key words such as "blade" and must have missed references to there being a current through the blade. Now I see.
You're welcome. Actually, besides the friction part it was a very good question. It helped me to analyze the whole situation and I now have a much better understanding myself, especially after thinking about the dough, razor blade, and butter knife analogy.
I have been doing all kinds of experiments lately, and as you might have guessed, some of these experiments have pertained to making a more opaque positive. In earlier posts you will see that I have experimented with fusing together double layer laser transparency prints. While this effectively makes a more opaque photo mask, I must admit that it is a slight pain to align and trim, therefore I doubt most DIYers would attempt this method. Still the fact remains, an opaque photo mask must be used to obtain high quality PCBs.
So how do you obtain an opaque photo mask for creating PCBs with the least amount of pain?
I currently do not have an answer to that question, but I may be onto something. After thinking about the problem for quite some time, I came to the conclusion that the biggest problem with laser printers is that it fades in large areas of black, such as a copper pour on a PCB. So my next question was, "Why does it fade in large areas of black?". So I began to investigate and experiment.
For my first experiment, I printed a 300 X 300 pixel filled black rectangle. Upon close examination, I noticed there was a very dense outline around the perimeter of the rectangle, and this outline was approximately 5 pixels wide, and furthermore, whatever was on the inside of the outline had the same type of shading (greyscale). So now I wondered, "Is this type of print shading (greyscale) specific to filled shapes or does it also apply to printed fonts?". So for my next experiment, I printed the letter "R" with a font size of 400. Since I already knew what I was looking for, no close examination was needed and it was readily apparent that the large "R" had the very same dense outline around the perimeter and the very same shading (greyscale) as the filled black rectangle.
Through these experiments I have come to the conlusion that the outline and shading is all software related to save toner. If the entire image could be printed with the same density as the outline, then perhaps a laser printer just might be capable of printing a very nice photo mask in one layer. Since both of my laser printers are Hewlett Packard LaserJet(s), I have ready access to two programming languages for controlling them, which are PJL and PCL. I don't know if either of these programming languages will allow me to alter this perimeter density and shading effects, but I definitely plan to investigate the possibilty.
As I've said on one or two occasions, a 1200 dpi inkjet printer costing $100 produces opaque transparencies when used with the correct material, without any problems. The fact that exposure and development times both have a lot of latitude indicate that the contrast is correct.
I used to use an HP laser printer to produce transparencies on both tracing paper and LaserStar film, and that worked OK, without messing about with the software. Exposure and development were also non-critical.
You should mention your problems to the Homebrew PCB Yahoo Group. Several people there use laser printers to produce their transparencies.
That is great for people that are willing to go drop $100 dollars for a new printer, but what about the people that have already have a laser printer and don't want to spend $100.
As you have already mentioned, and as Walt has hinted, this is a problem specific to laser printers, especially for copper pours.
It might be easily resolved with a few lines of code and I intend to find out.
Back when I was making homemade boards, I used either 2 mylars with laser or inkjet prints stacked on top of each other. I took 2 pieces of scotch tape, stuck them together so they overlapped a little to create a double sided piece of tape. I would make at least 4 of these pieces and then put one near the edge of the mylar(top, bot, l/r) and then press the mylar together in the art region. It would take maybe a minute to line it up and then press the tape areas together to lock the mylar on top of each other. Another trick is to print the image reversed so that the image is placed on the bottom side of the transparency against the board. This way there is even less light to travel 'around' the edge of the ink and create a less sharp impression. Of course it was required to press the glass against the mylar to force the ink layer onto the PCB. This was cheap and dirty, worked great.
Regarding lasers, I found that they provided no real benefit. A basic inkjet will do the job just fine, but I always stacked the film. Side note: Ordering boards is the only way to go in hind sight
Comments
Sorry to say that I have no photos. However, I did learn something new about my exposure box/cylinder and that I must make a new attachment for it. With the addition of some white vinyl and a small piece of glass, the bottom portion of the exposure box/cylinder makes an excellent light box for layout, alignment, and trimming purposes. I used this setup for aligning both transparency layers, spot fusing the transparencies together, and for trimming the double layer transparencies to size. The combination of this setup along with the film cutter/fuser, definitely helps to make less translucent double layer laser transparencies. It all works together pretty nice.
Bruce
'
A big problem I found using Laser printers is with Copper Pours.
'
I'm working with a lot of RF here lately and I need a good ground plain (copper pour) to help propagate the RF.
'
Have you been able to print copper pours with your laser printer with out making a mess?
How big a copper pour are you talking about? Can you provide an example? And are you talking about a mess on the board or with your printer?
Bruce
If you are referring to a mess with the printer.... If I remember correctly, you said you were using 3M transparency film. I would imagine that film is very similar to the film I initially used and it gave me many headaches. With the premium transparency film that I received from the local graphic arts supply house, the results are much better in all respects, including ground planes.
Bruce
Additionally, don't be afraid to touch up the ground planes on the photo mask with a black permanent marker.
Bruce
I just had a go at printing the top and bottom layers of that test PCB, but had problems printing from GC-Prevue and Pulsonix.
Have you been able to print them OK?
I apologize for the delay, but I just noticed your last post.
GC-Prevue prints out perfect masks for me. In fact, it allows me to add extra layers, such as the mounting holes, and prints them out as well.
There are three possible states for each layer, which are View, Edit, and Hide. When the layers are listed, there will be either an E, V, or H, at the beginning of the layer to represent its state. The layers should be in View state to allow printing.
To save you some trouble, I have attached a project file that includes the mounting holes. Perhaps this will work better for you.
Bruce
EDIT: Additionally, all layers that you do not want printed must be hidden.
EDIT: When printing, select the checkbox for: "Print all data in black"
EDIT: And of course, when printing the top layer, select the checkbox for: "Print as bottom view"
Just a friendly word of caution.
When spraying your photo mask films with Acrylic Krylon Crystal Clear Satin, the utmost care must be taken not to completely saturate the image, otherwise the toner will bleed to unwanted areas. It takes a few times to get the hang of it. And if it looks as though it has bled, believe it. Just print another mask and try again, because wasting a little film is much better than wasting additional time and board material. Trust me I know.
Bruce
Did that help?
In regard to the tips that I provided in Post #69, there is one thing I forgot to mention. Retain the default setting of "Layers To Print: VISIBLE" in the Print Setup property sheet, when using the tips I provided, or you can select individual layers from the Print Setup property sheet if you choose to do so, which will also print a hidden layer without altering the visibilty within the user interface view.
Bruce
The blades for the film cutter/fuser are burning up to often. They work great, but it is turning out to be a pain creating new blades all the time. As mentioned in Post #58, I am currently bending 0.047" music wire into a U-shaped form, and then sharpening one corner as described in Item #4 of the directions for that same post. I am not sure if they are burning up quickly because the music wire is tempered, too much carbon buildup on the blade from cutting the film, or some other reason.
I would like to find a solution with a little bit of longevity. Does anyone have any suggestions?
Bruce
Bruce,
I use these a lot for cutting foam shapes. They are actual blades and hold up very well. The price of admission is a little high though.
http://www.demandproducts.com/Hotwire-items/search.php?l1=8,15
Jim
However I was thinking more along the lines of my homemade cutter, with a different cutting blade. I found some 3/8 crown X 5/8 leg staples, and I have been experiment with them. If I could perfect the use of those, that would drastically cut the time required for making blades.
Bruce
Referring to Post #75. In an attempt to find a better blade material, I tried using 1/16" tie wire. It appeared that the wire held up well, but there was a drastic increase in the plastic buildup as compared to the 0.047" music wire. By the time I finished removing all the buildup, I had ruined the best looking photo mask that I have had in my hands.
Ohhh, and I finally kicked the circuit breaker in the battery charger with this last experiment
For a while, I have been considering the modification of a double-edged shaving blade. I may try that next. I will keep you posted.
Bruce
Why didn't I think of that a little sooner DUH
Bruce
The 0.032" music wire seemed to do okay with very little buildup, however, it seemed to burn out just a little faster than the 0.047" music wire. Additionally, it seemed that the 0.032" wire did not fuse the layers together as well as the 0.047" wire. I plan to do a little more experimenting with this wire size, because it will enable me to make my blades much faster using the wire bending CNC and I have lot of wire in this size. My main goal now is to get the two layers to fuse together properly. If I can achieve that, then I believe I will be able to create some nice masks fairly quickly and without the hassle of using a torch.
On a side note, when filing down any remaining plastic buildup, use a new or very clean file. Oil, dirt, and old metal shavings remaining on used files quickly destroy a good looking mask. Once again, I am speaking from the little experience I have gained through this experimentation process. However, I did previously mention to perform the filing procedure on the edge of a metal plate, so a new file will eventually gather small metal shavings. Just remember to keep the file as clean as possible and work in a very clean environment to keep the masks looking nice.
Oh, and there is something else you should know. If you make a film cutter/fuser and cut upon a piece of glass as I describe, each cut will leave a line of plastic resin upon your glass plate. This plastic resin can be removed with laquer thinner. Additionally, pressure and heat from the cutting action will cause permanent scratching upon the glass surface. Considering that the cutting wire gets red hot, if you leave it in one place for too long, it will melt the glass, thus making a permanent indentation.
Bruce
As it turns out, the 0.032" dia. music wire works pretty good for cutting and fusing the two layers of film together, however it requires several passes through the cut. Upon completion of trimming the mask, there is very little touchup required to remove the plastic buildup. I am sure there are probably much better solutions available, but this works pretty darn good, and considering that I have an abundance of this particular wire size and a machine to quickly bend the wire into shape and cut it, I believe this is the best solution for me. Please note, that in accordance with previous experiments for cutting blades, these cutting blades must also be sharpened as described in Item #4 of the Directions section of Post #58.
As I mentioned, this is a good solution for me, but if you decide to make a film cutter/fuser, you may want to experiment a bit more to find or create something that works much better. If you do find something that works much better, please let me know.
Bruce
Thanks,
Paul
The smaller wire heats up faster due to resistance.
The main idea is not to burn the plastic, but to slice through it by a melting process. As the blade is slicing through the two layers of film, the blade is hot on both sides, which results in both layers on both sides of the blade being melted and joined together.
As for the buildup, I believe this is all related to the actual thickness and bevel of the cutting portion of the blade. For instance, if you have a lump of bread dough on the counter and you slice through it with a razor blade, you will not have much buildup on either side of the blade. On the other hand, if you attempt to slice through the dough with the handle end of a butter knife, I would imagine the buildup would be pretty significant on both sides.
Remember, you do not want to burn anything, you want to melt it.
Bruce
Bruce
Thanks again for helping me understand.
Paul
You're welcome. Actually, besides the friction part
Thanks for the question.
Bruce
I have been doing all kinds of experiments lately, and as you might have guessed, some of these experiments have pertained to making a more opaque positive. In earlier posts you will see that I have experimented with fusing together double layer laser transparency prints. While this effectively makes a more opaque photo mask, I must admit that it is a slight pain to align and trim, therefore I doubt most DIYers would attempt this method. Still the fact remains, an opaque photo mask must be used to obtain high quality PCBs.
So how do you obtain an opaque photo mask for creating PCBs with the least amount of pain?
I currently do not have an answer to that question, but I may be onto something. After thinking about the problem for quite some time, I came to the conclusion that the biggest problem with laser printers is that it fades in large areas of black, such as a copper pour on a PCB. So my next question was, "Why does it fade in large areas of black?". So I began to investigate and experiment.
For my first experiment, I printed a 300 X 300 pixel filled black rectangle. Upon close examination, I noticed there was a very dense outline around the perimeter of the rectangle, and this outline was approximately 5 pixels wide, and furthermore, whatever was on the inside of the outline had the same type of shading (greyscale). So now I wondered, "Is this type of print shading (greyscale) specific to filled shapes or does it also apply to printed fonts?". So for my next experiment, I printed the letter "R" with a font size of 400. Since I already knew what I was looking for, no close examination was needed and it was readily apparent that the large "R" had the very same dense outline around the perimeter and the very same shading (greyscale) as the filled black rectangle.
Through these experiments I have come to the conlusion that the outline and shading is all software related to save toner. If the entire image could be printed with the same density as the outline, then perhaps a laser printer just might be capable of printing a very nice photo mask in one layer. Since both of my laser printers are Hewlett Packard LaserJet(s), I have ready access to two programming languages for controlling them, which are PJL and PCL. I don't know if either of these programming languages will allow me to alter this perimeter density and shading effects, but I definitely plan to investigate the possibilty.
Bruce
I used to use an HP laser printer to produce transparencies on both tracing paper and LaserStar film, and that worked OK, without messing about with the software. Exposure and development were also non-critical.
You should mention your problems to the Homebrew PCB Yahoo Group. Several people there use laser printers to produce their transparencies.
That is great for people that are willing to go drop $100 dollars for a new printer, but what about the people that have already have a laser printer and don't want to spend $100.
As you have already mentioned, and as Walt has hinted, this is a problem specific to laser printers, especially for copper pours.
It might be easily resolved with a few lines of code and I intend to find out.
Bruce
Regarding lasers, I found that they provided no real benefit. A basic inkjet will do the job just fine, but I always stacked the film. Side note: Ordering boards is the only way to go in hind sight